Toward an evolutionary containment of evolving pathogen-receptors by using an ensemble of multiple mutant ligands: from the viewpoint of fitness landscape in sequence space.

It is known that even if a ligand peptide is designed to bind to a target receptor on the surface of a pathogen such as viruses, bacteria or cancer cells, it is likely that some receptors are subject to random mutation and thus the ligand has a reduced ability to bind to these receptors. This issue is known as drug-resistant or escape mutants. In this paper, we present an idea to inhibit the evolving receptors by using an ensemble of all possible single- or double-point mutant sequences of the ligand peptide. Several mutant ligands in the ensemble are expected to bind to the mutant receptors, and then the ensemble may create a defensive wall surrounding the target receptors in receptor-sequence space. We examined the effectiveness of this "evolutionary containment" of the evolving receptors through eight peptide-protein complex systems, which were retrieved from the Protein Data Bank (PDB). As a result, we obtained a suggestion that the original (or parent) ligand sequence should be designed to have as high fitness as possible but to be not local optima, in order to maximize the rate of the evolutionary containment. This may be a strategy of the drug-design against evolving pathogens.